Department of Biology

Robert McLean

Professor
 

Phone: 512-245-3365

Fax: 512-245-8713

E-mail: McLean@txstate.edu

[ Mailing Address / Research Interests / Courses Taught / Publications / Theses Directed / Students & Postdocs ]

Mailing Address

Department of Biology
Texas State University
601 University Drive
San Marcos , TX 78666
 
 

Education

B. Sc. Microbiology, University of Guelph , 1978
Ph.D. Microbiology, with JW Costerton , University of Calgary , 1986
Postdoc with TJ Beveridge, University of Guelph , 1986 - 1988
Developmental Leave:

W ith Debby Siegele , Department of Biology, Texas A&M University , Fall 2000

With Marvin Whiteley, Molecular Genetics & Microbiology, University of Texas, Spring 2008
 

Memberships in Scientific Societies

American Society for Microbiology
Texas Branch, American Society for Microbiology (Region Planning Coordinator for ASM region 6 (2007-2009), covering Missouri Valley, Rio Grande, Rocky Mountain, and Texas ASM branches)

Asociación Mexicana de Microbiología, AC

Canadian Society of Microbiologists
International Society for Microbial Ecology

Sigma Xi Scientific Research Society
 

Research Interests

Biofilms: Most bacteria in their natural environments live on surfaces as slime-encased, biofilm communities. In contrast to their planktonic counterparts, sessile bacterial populations are significantly more resistant (by several orders of magnitude) to environmental stresses such as harmful chemicals, antibiotics and predation. While biofilms are the dominant form of growth of bacteria in nature, little is known about the biological factors that allow growth as biofilms. Studies in my lab, done in collaboration with Debby Siegele ,  Clay Fuqua , Walt Fast, Dhiraj Vattem, and Sandy Pierson , address three major aspects of bacterial physiology which are important in biofilm growth and development. These include the ability of individual bacteria to grow slowly, survive starvation stresses, express a variety of biofilm-activated genes, and for the organisms within a biofilm community to perform many metabolic activities as a group through a phenomenon known as quorum-sensing. Recently in collaboration with Marvin Whiteley and Tom Wood, we have expanded these studies by employing gene arrays and transcriptional profiling to investigate overall patterns of gene expression in mixed culture bacterial biofilms. 

Bacteria in nature, including those within biofilms, live as mixed populations. Therefore in order to understand natural biofilm growth, it is important to investigate microbial interactions in mixed communities. We have observed that bacterial community composition affects biofilm formation and susceptibility to iodine disinfection ( link to abstract ), and are now investigating whether quorum-sensing and other physiological activities affect biofilm community structure.

Aside from their importance on earth, biofilms may also impact the success of Payload patch for shuttle flight STS-95future long-term space flights due to possible fouling of water recycling filters. We recently flew an experiment in the John Glenn space shuttle (STS-95 ) to show that the bacterium, Pseudomonas aeruginosa, could form biofilms under weightless conditions ( link to abstract ).  In a follow-up experiment, we flew an Columbia picture showing payload behind astronaut Kalpana Chawlaexperiment on shuttle flight STS-107 , which STS-107 Mission Patchlaunched on January 16, 2003 to study biofilm formation and microbial competition in a three-member bacterial consortium. On February 1 2003 , during reentry, the space shuttle Columbia was destroyed along with all crew members . These include Commander Rick Husband, Pilot William McCool, Payload Commander Michael Anderson, Mission Specialist David Brown, Mission Specialist Kalpana Chawla, Mission Specialist Laurel Clark, and Payload Specialist Ilan Ramon. We mourn the loss of these seven outstanding people and offer our thoughts and prayers for their families and friends.    Appended is a photograph taken aboard Columbia during STS-107, showing Astronaut Kalpana Chawla with our payload visible in the upper left corner. Amazingly, our payload survived the impact and we gained access to it during the week of May 5, 2003. Some images can be seen at http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19550 , http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19539 , http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=19475 . We have found one organism in the payload that may have survived this disaster (McLean et al., Icarus 181: 323-325, 2006) (link to abstract). 

 

Microbial Mineral formation and nanobacteria: Bacteria and other microorganisms have been associated with the formation of many types of sedimentary rocks and minerals. Recently, small bacteria-shaped objects have been described by RL Folk, a geologist at the University of Texas . While these objects resemble bacteria, they are approximately 1/5 the size and have thus been termed nanobacteria (also spelled nannobacteria). Although initially thought to be independant life forms, our current thinking is that they are more likely to represent remnants of bacterial polymers (slime) and possibly outer membrane vesicles. Aside from their potential importance in geology, they have also been cited as evidence of extraterrestrial life on a recently described Martian meteorite. Nanobacteria research in my lab, in association with Robert L Folk (Geological Sciences , University of Texas ), Brenda L Kirkland and F Leo Lynch , (Geosciences , Mississippi State University ) seeks to ascertain the nature of nanobacteria and to investigate whether they are involved in mineral formation.

Courses Taught

BIO 2400: Microbiology

BIO 4445/5445: Pathogenic Microbiology

 

BIO 4447/7447: Microbial Physiology and Genetics

Internet Search Sites for Research Articles:


Microbiology Web Links

Other Links:

Publications

SELECTED PAPERS (1990 - present)

 

 

 

 

 

 

 

 

 

 

 

 

BOOKS

BOOK CHAPTERS


CONFERENCE PROCEEDINGS

 

Theses Directed

  1. S Nath 2009. "Potential Of Biofilms To Harbor Largemouth Bass Virus (LMBV)" MS Thesis, Texas State University-San Marcos
  2. MM Weber 2007.  "Role of yjfO, agaB and atoS in Escherichia coli Biofilm Formation and Stress Response"  MS Thesis, Texas State University-San Marcos  
  1. W Boswell 2007. "Effects of N-acyl-L-homoserine lactone lactonase on disruption of preformed biofilms, bacterial recruitment, and prevention of biofilms" MS Thesis, Texas State University-San Marcos
  2. MM Merchant 2005. " Identification and Characterization of Bacterial Isolates from Spring Lake, Texas", MS Thesis, Texas State University
  3. AK Welsh 2005. “Detection of an Introduced Bacterial Culture in Greywater Treatment Reactors“, MS Thesis, Texas State University
  4. CL Bates 2004. “Differential Gene Expression and Colanic Acid Gene Effects on Biofilm Formation” MS thesis, Texas State University
  5. KL Fuson 2002. “Biofilm-Induced Gene Expression in Chemostat Grown Escherichia coli as Determined by a Gene Array” MS thesis, Southwest Texas State University
  6. MK Windham 2001. "Acyl Homoserine Lactone Recruitment of Bacteria Into Biofilms" MS thesis, Southwest Texas State University
  7. GJ Balzer 2000. "Effect of relA and spoT Deletions on Escherichia coli Biofilm Formation" MS thesis, Southwest Texas State University
  8. Corbin, B.D. 2000 "Replication of T4 Phage in an Escherichia coli Biofilm", MS thesis, cosupervised with G Aron , Southwest Texas State University
  9. Prabhakaran, S. 1999. "Investigation of Bacterial Fragmentation as a Possible Origin of Nanobacteria" MS thesis, Southwest Texas State University
  10. Adams, J.L.   1998   "Role of rpoS in the Formation and Physiology of Escherichia coli Biofilms" MS thesis, Southwest Texas State University
  11. Knowles, H.C.  1998  "The Isolation, Culturing, and Characterization of Nannobacteria" MS thesis, Southwest Texas State University
  12. Khu, P.T.  1998  "Bacterial Precious Metal Recovery". MSc ( Eng. ) thesis, Queen's University (co-supervised with W.T. Yen , Mining Engineering, Queen's University)
  13. Whiteley, M.  1997  "Effects of Nutrient Limitation and Species Composition on Biofilm Development and Susceptibility to Iodine Disinfection". MS thesis, Southwest Texas State University
  14. Koenig, M.K.  1996  "Parameters Affecting the Conformation of N-acetylneuraminic acid, Escherichia coli K1 Capsular Polysaccharide" MS thesis, Southwest Texas State University
  15. Vincent, P.J.  1995 "Silver-platinum Multilayer Thin Films as Antimicrobial Coatings for Catheters". MSc ( Eng. ) Thesis, Queen's University (co-supervised with M Sayer, Physics, Queen's University)
  16. Persaud, A.T.  1994  "Development of Inductively-Coupled Plasma-Mass Spectrometry for Soil Analysis" MSc Thesis, Queen's University (co-supervised with D Beauchemin, Chemistry and HE Jamieson , Geological Sciences, Queen's University )
  17. Dumanski, A.J.  1992  "Isolation and Characterization of the Capsule of Proteus mirabilis and its Role in Kidney Stone Formation". MSc Thesis, Queen's University

Honors Theses:

  1. V Pearson 2004 “Antibiotic Resistance of Biofilms”. BS Honors Thesis, Texas State University-San Marcos
  2. AR Primmer 1999 "Using Transposon Mutagenesis to Analyze Antibiotic Resistance in Pseudomonas aeruginosa Biofilms". BS Honors Thesis, Southwest Texas State University
  3. EJ Hughes 1996 "Efficiency of Latex Gloves as Barriers to Bacterial and Viral Pathogens". BS Honors Thesis, Southwest Texas State University
  4. HL Bates 1996 "Bacterial Biofilm-Associated Infection in Indwelling Medical Devices". BS Honors Thesis, Southwest Texas State University
  5. KA Dunn 1995 "Role of Bacterial Biofilms in Leaf Fossilization". BS Honors Thesis, Southwest Texas State University (co-supervised with G.R. Upchurch, Biology, Southwest Texas State University)

Students, Research Associates & Postdocs (the Slime Gang)

Slime Gang and Friends, Glove Party 2006 (from left) Diane Fitzgerald (Kimberley-Clark), Jim (Buddy) Gaertner, Bob McLean, Allana Welsh, Shannon Kruse (Cuevas Distributing), Will Boswell, Mikki Boswell, Pejmon Afshar, Monte Gomez, Celeste Whisenant, Mary Weber, and Ian O'Leary

 

2008 Pizza Party (Slime Gang and Friends)

(Front row L-R: Maria Jimenez, Mary Weber, Tommy Erwin, Lindsey Wiggins, Kimberly Kuhler-Dabbs, Dittmar Hahn)

(Back row standing L-R: Gary Aron, Babur Mirza, Shubhankar Nath, Bob McLean; seated L-R Jim (Buddy) Gaertner, Allana Welsh, Gulam Pasual (visiting scientist with Dittmar Hahn))

 

Students:

 

Research Associates: Mary Weber, Lecturer and Research Associate

 

Postdoc:   Weihua Chu

Visiting Scientists: None

Honorary Lab Members:

Slime Gang Alumni

Graduate Students:

Undergraduate Students:

 

Technicians and Lab Visitors:

Last updated Tuesday, April 21, 2009. Click here to return to the Biology front page.